- Who discovered the neutron?
a) J.J. Thomson
b) Chadwick
c) Rutherford
d) Priestley
Answer: b - Which of the following elements has a higher atomic number than copper?
a) Iron
b) Chromium
c) Zinc
d) Manganese
Answer: c - The photoelectric effect involves the emission of electrons when:
a) The metal is heated
b) The metal is placed in an electric field
c) High-speed electrons strike the surface
d) Light of suitable frequency falls on the metal surface
Answer: d - An atomic orbital is defined as:
a) A circular path of the electron
b) An elliptical orbit
c) A three-dimensional region around the nucleus
d) A region where the probability of finding an electron is maximum
Answer: d - Bohr’s model successfully explains:
a) The spectrum of hydrogen atoms
b) The spectrum of any atom with two electrons
c) The spectrum of hydrogen molecules
d) The solar spectrum
Answer: a - When an electron falls from a higher to a lower energy level:
a) Energy is absorbed
b) Energy is emitted
c) Atomic number increases
d) Atomic number decreases
Answer: b - Atoms of different elements have:
a) Same atomic number and configuration
b) Different atomic number but same configuration
c) Different atomic number and different valence electrons
d) Same number of electrons and neutrons
Answer: c - The concept of dual nature of radiation was proposed by:
a) Max Planck
b) De Broglie
c) Heisenberg
d) Pauling
Answer: b - An element has atomic number 17 and mass number 36. How many neutrons are present?
a) 17
b) 19
c) 36
d) 53
Answer: b - The element with atomic number 29 belongs to:
a) s-block
b) d-block
c) p-block
d) f-block
Answer: b - The antiparticle of an electron is:
a) Positron
b) Proton
c) Alpha particle
d) Beta particle
Answer: a - Fundamental particles of an atom include:
a) Proton, electron, meson
b) Proton, electron, photon
c) Proton, electron, neutron
d) Proton, electron, deuteron
Answer: c - The species ⁴⁰Ar₁₈, ⁴⁰K₁₉, ⁴⁰Ca₂₀ are called:
a) Isotones
b) Isotopes
c) Isobars
d) None of these
Answer: c - The order of orbital filling in atoms is governed by:
a) Aufbau principle
b) Heisenberg uncertainty principle
c) Hund’s rule
d) Pauli’s exclusion principle
Answer: a - When metals are heated in flame, electrons jump to higher energy levels. On returning to lower levels, they emit:
a) Raman spectrum
b) Absorption spectrum
c) Emission spectrum
d) Fluorescence
Answer: c - Regarding Bohr’s atomic model, which are correct?
- It introduces stationary orbits
- It assumes quantized angular momentum
- It uses a planetary model with circular orbits
a) 1 and 2
b) 2 and 3
c) 1 and 3
d) 1, 2 and 3
Answer: d
- Atomic size is approximately:
a) 10⁻⁸ cm
b) 10⁻¹⁰ cm
c) 10⁻¹³ cm
d) 10⁻⁶ cm
Answer: b - Which of the following is NOT true about X-rays?
a) They have low energy
b) They travel at the speed of light
c) They can be refracted
d) They affect photographic plates
Answer: a - The size of the atomic nucleus is measured in:
a) amu
b) Angstrom
c) cm
d) Fermi
Answer: d - Which element has only two electrons in the K-shell?
a) Hydrogen
b) Helium
c) Neon
d) Sulphur
Answer: b - The nucleus of an atom contains:
a) Protons
b) Neutrons
c) Protons and neutrons
d) Electrons, protons, and neutrons
Answer: c - Which of the following is NOT a nucleon?
a) Proton
b) Electron
c) Neutron
d) Positron
Answer: b - Number of p-electrons in a bromine atom:
a) 12
b) 15
c) 7
d) 17
Answer: d - Which particle has the greatest mass?
a) Electron
b) Proton
c) Neutron
d) Hydrogen nucleus
Answer: c - The mass of a proton is approximately equal to the mass of a:
a) Neutron
b) Electron
c) Isoprone
d) Alpha particle
Answer: a